This invention relates generally to the field of material handling, and more particularly to an improved mechanism for transporting small articles from a first location to a second location, as might be involved during the manufacture of semi-conductor chips and the like. The disclosed construction is equally useful in the placing of a small component such as a label upon a container as the container proceeds along an assembly line. Such devices normally include a vacuum head for engaging and releasing the transported article, and are commonly referred to as pick and place mechanisms. Devices of this general type are known in the art, and the invention lies in the provision of an improved type of device offering improved adjustment capability, simplification of structure, and improved operation with corresponding ease of manufacture and resulting lower cost of production.
In the prior art, devices of this type have usually included a pneumatic cylinder which drives a spindle mounting a vacuum head on a free end thereof. The spindle is advanced and retracted as required along its own axis, to pick up or place the workpiece, and is transported in a plane normal to the axis of the spindle to move the workpiece from one location to another. Pneumatically operated devices are not without substantial utility, but they are accompanied by substantial disadvantages inherent in pneumatic operation. The principal problems are the lack of control or programmability with respect to stroke length, difficulty in monitoring spindle position along its axis, and excessive size, particularly when the workpiece is quite small. In addition, the pneumatic piston is often free to rotate about its own axis during operation, which can result in improper positioning of the workpiece at the place location. These shortcomings can be ameliorated only to a limited degree.